The hybridizable discontinuous Galerkin (HDG) methods were originally introduced
about a decade ago in [1]} for diffusion problems as a subclass
of discontinuous Galerkin finite element methods
amenable to static condensation and hence to efficient implementation.
Since then, the HDG methodology has been successfully applied to a variety of
problems in computation fluid dynamics and continuum mechanics [2]}, [3]}, [4]}, [5]}.
